Measurement Uncertainty as a Criterion for Analytical Method Selection in Quality Assurance Systems

Piotr PRZYBEK

Abstract:

The determination of sulfur dioxide (SO₂) content is one of the most frequently performed analyses in the wine industry. Ensuring the highest quality of the final product requires careful and responsible management of this preservative (Przybek, 2017).

In oenological laboratories, the measurement of free and total sulfur dioxide is a routine procedure, conducted at weekly or monthly intervals as an integral part of quality control processes. Most well-managed wineries perform SO₂ measurements both before and after its addition to the product. The pre-addition measurement helps determine the required dosage, while the post-addition measurement verifies its effectiveness (Jackson, 2020).

An ideal method for determining sulfite content in wine should provide accurate and reliable quantification within the typical concentration ranges found in wine, be rapid, cost-effective, and minimally labor-intensive, allow for the determination of both free and total SO₂, and ensure operator safety during the analysis.

The measurement of SO₂ content is of critical importance due to several key factors:

  • Regulatory compliance: Current regulations establish maximum allowable sulfite concentrations (expressed as SO₂) and mandate that wine labels disclose this information.
  • Aging process monitoring: Sulfite levels decline during wine aging, necessitating careful monitoring to determine the required replenishment dosage.
  • Sensory quality preservation: Excessive sulfite concentrations can lead to undesirable taste and odor alterations, negatively affecting the wine’s organoleptic properties.
  • Health considerations: Approximately 1 in 100 individuals exhibits sulfite sensitivity. These range from mild reactions (such as skin irritation, headaches, or asthma exacerbation) to severe complications (including anaphylactic shock).

This article aims to compare the applicability of the spectrophotometric method for determining total sulfite content in red wines (Tobeña, Muñoz, Dueñas i López, 2014) with the reference distillation method (OIV, 2019). The comparison is based on an uncertainty assessment of both methods, evaluating their precision, accuracy, and suitability for routine laboratory use.